This invention relates to a multi-probe unit and a measuring apparatus using same in which extreme ends of probes formed at end portions of conducting wires are in contact with a number of densely arranged conductor patterns, and opposite ends or the conducting wires are electrically connected to a measuring apparatus.
For the purpose of electrically inspecting substrates having arrays of semiconductor elements and TFT (thin film transistor) liquid crystal display elements, widely used is a method of using a number of metal fine needles and bringing them into contact with electrodes formed on elements thereby to make electrical contact of these elements, external power source and measuring apparatus.
Along with the recent tendency and development toward higher speeds and higher performances of semiconductor elements and liquid crystal display elements, it has become a common knowledge to shield needles for preventing mixture of electric noise generated around probes and cross-talk between probes.
FIG. 2A is a perspective view showing configuration of a shielded conductor line 1 forming a probe, and FIG. 2B is a perspective view showing general configuration of a multi-probe unit 10 in which a number of shielded conducting wires are fixed. In FIG. 2A, the shielded conductor line 1 is composed of a central conductor 2, insulator 3 and metal tube 4. Among these components, the central conductor 2 is typically made of tungsten or other hard metal. Its first end 2a extends beyond the insulator 3 and the metal tube 4 by a predetermined length, and its extreme end is bent like a hook and sharpened to form a probe needle 5. The opposite second end of the central conductor 2 extends beyond the insulator 3 and the metal tube 4 by an enough length for electrical connection. The insulator 3 is a tube member of an insulating material such as polyethylene, which wraps the central conductor 2. The metal tube 4 as a shielding member covers it from outside, and this metal tube 4 is connected to a ground potential to prevent mixture of electrical noise and generation or cross talk between probes.
The multi-probe unit 10 shown in FIG. 2B is made by fixing such shielded conducting wires 1 on the bottom surface of a printed circuit board (PCB) 11. In this case, although only apart thereof is illustrated for simplicity, the shielded conducting wires 1 are fixed on the printed circuit board 11 by a conductor fixing member 12 made by injection molding, for example, such that their probe needles 5 be aligned with substantially equal distances at the location for connection with electrodes 21 on a liquid crystal display substrate 20, and they radially spread out from their first ends with the probes 5 toward their opposite second ends. In this case, the conductor fixing member 12 is located at a front end of the printed circuit board 11, and on a rear end portion of the printed circuit board 11, connector jacks 13 as many as the shielded conductors 1 are fixed, with their terminals connected to the second ends 2b of the central conductors 2.
Each central conductor 2 forming the shielded conductor 1 has the diameter of about 0.2 mm, and the diameter of the shielded conductor line 1 exceeds approximately 0.5 mm. On recent substrates having arrays of TFT liquid crystal display elements, the pitch of electrodes is getting narrower, and in some cases, their interval is as small as 50 xcexcm approximately. To bring tips of probe needles 5 into contact with such densely arranged electrodes, even when the shielded conducting wires 1 were densely arranged to radially extend and also overlap in vertically different stages, the minimum pitch of electrodes enabling contact with tips of probe needles was only 200 xcexcm approximately.
Further, even in the case of electrodes aligned at intervals of approximately 200 xcexcm, when the number of electrodes is 20 or more, a multi-probe unit 10 was made by using covered conducting wires without the metal tubes 4, that is, covered conducting wires made of only central conductors 2 and insulators 3, at the cost of the countermeasure against noise and cross talk. Therefore, even with electrodes aligned at intervals of 50 xcexcm, it was compelled to use covered conducting wires made of only central conductors 2 and insulators 3.
Recently, there have been developed liquid crystal display devices in which scanning line driving circuits and video signal line driving circuits for driving liquid crystal display elements using TFT of polysilicon as their components are incorporated together with the liquid crystal display devices on common substrates, LSIs using TAB (tape automatic bonding) technique to apply scanning pulses to scanning lines and video signals to video signal lines, and so on. When these devices were electrically inspected with multi-probe units using covered conducting wires, explained above, the tests were liable to be adversely affected by noise and cross talk, and this inspection technique involved the problem to be overcome, namely, unavailability beyond limited items of inspection and insufficient inspection performance.
It is therefore an object of the invention to provide a multi-probe unit and a measuring apparatus using same, which can reduce mixture of noise from outside and cross talk to a practically negligible level and thereby improve the electrical inspection performance even when using covered conducting wires made of only conducting wires and insulators.
According to the invention, there is provided a multi-probe unit having conducting wires which have first end portions forming probes whose extreme ends contact with a number of densely arranged conductor patterns and second ends electrically connected to a measuring apparatus, comprising: a substrate which can be held from outside; a number of covered conducting wires each made of a central conductor whose intermediate portion except opposite end portions thereof is covered by an insulating cover, each central conductor having a first end portion which is bent to form the probe; a conductor fixing member for holding extreme ends of the probes of the covered conducting wires in alignment at substantially the same intervals as those of the conductor patterns, then radially spreading intermediate portions of the covered conducting wires relative to the first end portions thereof, and fixing the intermediate portions of the covered conducting wires such that the intermediate portions be alternately positioned in different locations which are different in distance from the substrate; and a shield plate interposed between the conductor layers to electromagnetically shield the conductor layers from each other.
According to the invention, there is further provided a multi-probe unit used for electrical inspection and having a plurality of probes for contact with a plurality of conductor patterns to be inspected which are aligned side by side, in which every two adjacent ones of the probes for contact with odd-numbered one and even-numbered one of the conductor patterns are positioned in upper and lower levels distant in the thickness direction, and a shield plate of a conductive material having an electrically shielding function is interposed between the upper and lower probes.
According to the invention, there is further provided a measuring apparatus having an external device having at least a built-in measuring device, and a multi-probe unit which is electrically connected to the external device, characterized in: the multi-probe unit having conducting wires which have first end portions forming probes whose extreme ends contact with a number of densely arranged conductor patterns and second ends electrically connected to a measuring apparatus, and including a substrate which can be held from outside; a number of covered conducting wires each made of a central conductor whose intermediate portion except opposite end portions thereof is covered by an insulating cover, each central conductor having a first end portion which is bent to form the probe; a conductor fixing member for holding extreme ends of the probes of the covered conducting wires in alignment at substantially the same intervals au those of the conductor patterns, then radially spreading intermediate portions of the covered conducting wires relative to the first end portions thereof, and fixing the intermediate portions of the covered conducting wires such that the intermediate portions be alternately positioned in different locations which are different in distance from the substrate; and a shield plate interposed between the conductor layers to electromagnetically shield the conductor layers from each other.
According to the invention, there is further provided a measuring apparatus comprising: an external device having at least a built-in measuring device; and a multi-probe unit which is electrically connected to the external device, and has a plurality of probes for contact with a plurality of conductor patterns to be inspected which are aligned side by side, in which every two adjacent ones of the probes for contact with odd-numbered one and even-numbered one of the conductor patterns are positioned in upper and lower levels distant in the thickness direction, and a shield plate of a conductive material having an electrically shielding function is interposed between the upper and lower probes.